1. Field of the Invention
The present invention relates to a method of manufacturing glass parts for connection of optical fibers, method of manufacturing mother glass to produce glass parts, and glass parts for connection of optical fibers.
2. Prior Art
Generally, in optical communication systems and optical applied equipment, optical connectors are used to connect optical fibers or connect an optical fiber and a light emitting/receiving device or the like.
Conventionally, optical connectors of this kind are divided into a split type as disclosed in Japanese Patent (KOUHOU) No. 2788800 and an integral type as shown in cross section in FIG. 17.
The integral type optical connector shown in FIG. 17 is comprised of a cylindrical glass ferrule 10 having a through hole 11 with a small diameter formed therein along a longitudinal central axis thereof. Optical fibers 12 and 13 are held in the through hole 11 with end faces 14 thereof abutting against each other. A matching agent (epoxy adhesive agent or ultraviolet hardening resin) is filled between the end faces 14. The matching agent acts to match the refractive index between the optical fibers 12 and 13, as well as bond the optical fibers together. The through hole 11 is tapered at its opposite open ends 15 and 16, so as to facilitate insertion of the optical fibers 12 and 13 into the through hole 11. The matching agent or an adhesive agent is filled in the open ends 15 and 16, and in gaps between the wall of the through hole 11 and the optical fibers 11 and 12 in order to fix the optical fibers 12 and 13 inside the through hole 11.
The ferrule 10 constructed as above is manufactured by forming a mother glass having a similar cross section to that of the ferrule, forming a through hole in the mother glass by machining, then drawing the mother glass with a through hole thus formed while heating the same to obtain a drawn glass, and then cutting the drawn glass into a suitable length. In manufacturing the ferrule 10, the formation of the mother glass and the through hole may be performed by press molding.
The ferrule 10 which is manufactured in the above described manner requires to have dimensional tolerances of ±3″5 μm of the cross-sectional size of the through hole 11, so as to locate the optical fibers with an accuracy of the order of light wavelength.
According to the conventional manufacturing method described above, sufficient dimensional accuracy of the cross-sectional size of the through hole 11 cannot be achieved because the ferrule 10 is formed by hot drawing a prepared mother glass. As a result, the optical fibers 12 and 13 cannot be smoothly inserted into the ferrule 10, nor held in place with accuracy.
Further, the process of forming a through hole in the mother glass to manufacture the ferrule 10 by machining or by press molding takes much time and labor to perform.
In addition, the conventional ferrule 10 is solely designed to make a connection between single optical fibers and cannot make a connection between groups of plural optical fibers